The present invention is related to fiberoptic network devices and systems, and in particular, to cholesteric liquid crystal cell devices and switch systems.
In fiberoptic networks light signals are used to carry information over optical fibers. Different techniques are used to control optical signals from the sender to the receiver. For example, time slots (time division multiplexing) or wavelengths (wavelength division multiplexing) may be used to define communication channels over an optical fiber. To carry out these operations, fiberoptic networks use many devices and systems of varying complexity. But speed has always been a prime objective in network operations. Hence one goal has been the creation of all-optical fiberoptic networks. Rather than converting incoming optical signals to electrical signals which are then processed by the network device or system and then reconverted back to outgoing optical signals, an all-optical network maintains the communication signals as optical signals as they pass through the network devices and systems. In this manner, the network loses no conversion time.
One promising technology toward this goal has been microelectromechanical system (MEMS) switches. Though there are many variations, the basic operation of a MEMS switch is the direction of light beams from an array of input optical fibers into an array of output optical fibers by an array of mirrors which selectively direct the incoming light beams to the arrayed ends of the output optical fibers. The position of each mirror is controlled by the selective application of deflection voltages. As the name implies, the mirrors in MEMS switches are also very small to provide the theoretical advantages of higher operational speeds due to the small inertial mass of the mirrors, lowered manufacturing costs from semiconductor processing circuit technology used to manufacture the mirror array with lower unit costs, and ease of installation and maintenance from the presumed small size of the MEMS switch. However, these advantages have not been realized thus far. Reliability, a prime concern for all networks, has reportedly been a problem with MEMS switches. Apparently the mechanical properties of these systems, the stress and strain on the mirrors (or their supports), add to the complexity of the systems and detract from their reliability.
To avoid these problems, the present invention utilizes cholesteric liquid crystal cells which form network devices and systems without the mechanical disadvantages of a MEMS and other optomechanical systems. Furthermore, the network devices and systems of the present invention retain the advantages of small size described above.